In a Time Division Duplexing (TDD) microwave system, an antenna for receiving and transmitting signals may be an electrical tilt array antenna. An antenna includes a group of array antennas, and each adjustable antenna array element in an array antenna has a phase shifter. The phase shifter performs control by using an electrical signal, so that an expected beam is generated on the array antenna by using the phase shifter. Moreover, the phase shifter can adjust a phase shift angle, and therefore beams of different angles can be generated by using the phase shifter. In the TDD microwave system, two devices perform bidirectional signal transmission between each other by separately using different time intervals, that is, timeslots. Therefore, before communication is established, not only beam alignment but also timeslot synchronization needs to be performed on the two devices.
In the prior art, the TDD microwave system uses an independent time serving device, such as a Global Positioning System (GPS) device. The system first uses the GPS device to calibrate clocks of the two devices, and then uses the calibrated clocks to synchronize timeslots in a timeslot structure, so that the two devices detect corresponding beam signals in the synchronized timeslots, to complete automatic beam alignment.
During implementation of the foregoing beam alignment, the two devices need to detect corresponding beam signals in the synchronized timeslots after the time serving device completes timeslot synchronization, so as to complete automatic beam alignment. In this way, a beam alignment process needs to be performed after timeslot synchronization, and consequently, the timeslot synchronization can be completed only by using the time serving device, which increases system complexity and reduces system flexibility.